Juicy and sweet and renowned for its concentration of vitamin C, oranges make the perfect snack and add a special tang to many recipes; it is no wonder that they are one of the most popular fruits in the world. Oranges are generally available from winter through summer with seasonal variations depending on the variety.
Oranges are round citrus fruits with finely-textured skins that are, of course, orange in color just like their pulpy flesh; the skin can vary in thickness from very thin to very thick. Oranges usually range from approximately two to three inches in diameter.
In recent research studies, the healing properties of oranges have been associated with a wide variety of phytonutrient compounds. These phytonutrients include citrus flavanones (types of flavonoids that include the molecules hesperetin and naringenin), anthocyanins, hydroxycinnamic acids, and a variety of polyphenols. When these phytonutrients are studied in combination with oranges—vitamin C, the significant antioxidant properties of this fruit are understandable.
But it is yet another flavanone in oranges, the herperidin molecule, which has been singled out in phytonutrient research on oranges. Arguably, the most important flavanone in oranges, herperidin has been shown to lower high blood pressure as well as cholesterol in animal studies, and to have strong anti-inflammatory properties. Importantly, most of this phytonutrient is found in the peel and inner white pulp of the orange, rather than in its liquid orange center, so this beneficial compound is too often removed by the processing of oranges into juice.
You may already know that oranges are an excellent source of vitamin C but do you know just how important vitamin C and oranges are for good health? Vitamin C is the primary water-soluble antioxidant in the body, disarming free radicals and preventing damage in the aqueous environment both inside and outside cells. Inside cells, a potential result of free radical damage to DNA is cancer. Especially in areas of the body where cellular turnover is especially rapid, such as the digestive system, preventing DNA mutations translates into preventing cancer. This is why a good intake of vitamin C is associated with a reduced risk of colon cancer.
Free radical damage to other cellular structures and other molecules can result in painful inflammation, as the body tries to clear out the damaged parts. Vitamin C, which prevents the free radical damage that triggers the inflammatory cascade, is thus also associated with reduced severity of inflammatory conditions, such as asthma, osteoarthritis, and rheumatoid arthritis.
Free radicals also oxidize cholesterol. Only after being oxidized does cholesterol stick to the artery walls, building up in plaques that may eventually grow large enough to impede or fully block blood flow, or rupture to cause a heart attack or stroke. Since vitamin C can neutralize free radicals, it can help prevent the oxidation of cholesterol.
Vitamin C, which is also vital for the proper function of a healthy immune system, is good for preventing colds and may be helpful in preventing recurrent ear infections.
Consuming vitamin C supplements does not provide the same protective benefits as drinking a glass of orange juice, shows research by Italian researchers in the Division of Human Nutrition at the University of Milan, Italy (Guarnieri S, Riso P, et al., British Journal of Nutrition).
Seven healthy test subjects were given each of three drinks, two weeks apart: blood-orange juice containing 150 milligrams of vitamin C, fortified water containing 150 milligrams of vitamin C, and a sugar and water solution containing no vitamin C. Blood samples were collected immediately before the drink was consumed, then every hour for 8 hours, and finally 24 hours after consumption of each drink.
Blood samples were exposed to hydrogen peroxide, and free radical damage to DNA was evaluated at 3 and 24 hours. Only when orange juice was consumed was any protective effect seen. After drinking orange juice, DNA damage was 18% less after 3 hours, and 16% less after 24 hours. No protection against DNA damage was seen after consumption of the vitamin C fortified drink or the sugar drink.
While another study, which looked at much larger quantities of vitamin C, did show a protective effect from the vitamin alone, this research indicates that not only is the protection afforded by fruit more complex, but smaller amounts of nutrients like vitamin C are all that are needed for benefit.
Said lead researcher, Serena Guarnieri, "It appears that vitamin C is not the only chemical responsible for antioxidant protection." In oranges, vitamin C is part of a matrix involving many beneficial phytochemicals (for example, cyanidin-3-glucoside, flavanones and carotenoids)."But how they are interacting is still anyone's guess," she added. Fortunately, we don't have to wait until scientists figure this out to receive oranges' DNA-protective benefits. Practical Tip: For the best DNA protection, skip the vitamin C—fortified bottled drinks and enjoy a glass of real (preferably organic as organic foods have been shown to contain higher amounts of phytonutrients), freshly squeezed orange juice—or simply eat an orange!
Owing to the multitude of vitamin C's health benefits, it is not surprising that research has shown that consumption of vegetables and fruits high in this nutrient is associated with a reduced risk of death from all causes including heart disease, stroke and cancer.
A 248-page report, "The Health Benefits of Citrus Fruits," released December 2003 by Australian research group, CSIRO (The Commonwealth Scientific and Industrial Research), reviews 48 studies that show a diet high in citrus fruit provides a statistically significant protective effect against some types of cancer, plus another 21 studies showing a non-significant trend towards protection.
Citrus appears to offer the most significant protection against esophageal, oro-phayngeal/laryngeal (mouth, larynx and pharynx), and stomach cancers. For these cancers, studies showed risk reductions of 40-50%.
The World Health Organization's recent draft report, "Diet, Nutrition and the Prevention of Chronic Disease," concludes that a diet that features citrus fruits also offers protection against cardiovascular disease due to citrus fruits—folate, which is necessary for lowering levels of the cardiovascular risk factor, homocysteine; their, potassium, which helps lower blood pressure, protecting against stroke and cardiac arrhythmias; and the vitamin C, carotenoids and flavonoids found in citrus fruits, all of which have been identified as having protective cardiovascular effects.
One large US study reviewed in the CSIRO report showed that one extra serving of fruit and vegetables a day reduced the risk of stroke by 4%, and this increased by 5-6 times for citrus fruits, reaching a 19% reduction of risk for stroke from consuming one extra serving of citrus fruit a day.
The CSIRO Report also includes evidence of positive effects associated with citrus consumption in studies for arthritis, asthma, Alzheimer's disease and cognitive impairment, Parkinson's disease, macular degeneration, diabetes, gallstones, multiple sclerosis, cholera, gingivitis, optimal lung function, cataracts, ulcerative colitis and Crohn's disease.
Finally, the CSIRO Report notes that as low fat, nutrient-rich foods with a low glycemic index, citrus fruits are protective against overweight and obesity, conditions which increase the risk of heart disease, certain cancers, diabetes, high blood pressure and stroke, and add to symptoms of other conditions like arthritis.
An orange has over 170 different phytonutrients and more than 60 flavonoids, many of which have been shown to have anti-inflammatory, anti-tumour and blood clot inhibiting properties, as well as strong antioxidant effects.
Phytonutrients, specifically, the class of polyphenols, are high in citrus with oranges containing 84mg Gallic Acid equivalents/100mg. The polyphenols so abundant in oranges have been shown to have a wide range of antioxidant, anti-viral, anti-allergenic, anti-inflammatory, anti-proliferative and anti-carcinogenic effects. Although most of the research has centered on citrus polyphenols—possible role in cancer and heart disease, more recently, scientists have begun to look at their role in brain functions such as learning and memory.
An increasing number of studies have also shown a greater absorption of the nutrients in citrus when taken not as singly as supplements, but when consumed within the fruit in which they naturally appear along with all the other biologically active phytonutrients that citrus fruits contain.
In animal studies and laboratory tests with human cells, compounds in citrus fruits, including oranges, called limonoids have been shown to help fight cancers of the mouth, skin, lung, breast, stomach and colon. Now, scientists from the US Agricultural Research Service have shown that our bodies can readily absorb and utilize a very long-acting limonoid called limonin that is present is citrus fruits in about the same amount as vitamin C.
In citrus fruits, limonin is present in the form of limonin glucoside, in which limonin is attached to a sugar (glucose) molecule. Our bodies easily digest this compound, cleaving off the sugar and releasing limonin.
In the ARS study, 16 volunteers were given a dose of limonin glucoside in amounts ranging from those that would be found in from 1 to 7 glasses of orange juice. Blood tests showed that limonin was present in the plasma of all except one of the subjects, with concentrations highest within 6 hours after consumption. Traces of limonin were still present in 5 of the volunteers 24 hours after consumption!
Limonin's bioavailability and persistence may help explain why citrus limonoids are potent anti-carcinogens that may continuously prevent cancerous cells from proliferating. Other natural anti-carcinogens are available for much less time; for example, the phenols in green tea and chocolate remain active in the body for just 4 to 6 hours.
A class of compounds found in citrus fruit peels called polymethoxylated flavones (PMFs) have the potential to lower cholesterol more effectively than some prescription drugs, and without side effects, according to a study by U.S. and Canadian researchers that was published in the Journal of Agricultural and Food Chemistry.
In this study, when laboratory animals with diet-induced high cholesterol were given the same diet containing 1% PMFs (mainly tangeretin), their blood levels of total cholesterol, VLDL and LDL (bad cholesterol) were reduced by 19-27 and 32-40% respectively. Comparable reductions were also seen when the animals were given diets containing a 3% mixture of two other citrus flavonones, hesperidin and naringin.
Treatment with PMFs did not appear to have any effect on levels of beneficial HDL cholesterol, and no negative side effects were seen in the animals fed the PMF-containing diets.
Although a variety of citrus fruits contain PMFs, the most common PMFs, tangeretin and nobiletin, are found in the peels of tangerines and oranges. Juices of these fruits also contain PMFs, but in much smaller amounts. In fact, you'd have to drink about 20 glasses of juice each day to receive an amount of PMFs comparable in humans to that given to the animals. However, grating a tablespoon or so of the peel from a well-scrubbed organic tangerine or orange each day and using it to flavor tea, salads, salad dressings, yogurt, soups, or hot oatmeal, buckwheat or rice may be a practical way of achieving some cholesterol-lowering benefits. The researchers are currently exploring the mechanism of action by which PMFs lower cholesterol. Based on early results in cell and animal studies, they suspect that PMFs work like statin drugs, by inhibiting the synthesis of cholesterol and triglycerides inside the liver.
Oranges' health benefits continue with their fiber, which has been shown to reduce high cholesterol levels thus helping to prevent atherosclerosis. Fiber can also help out by keeping blood sugar levels under control, which may help explain why oranges can be a very healthy snack for people with diabetes. In addition, the natural fruit sugar in oranges, fructose, can help to keep blood sugar levels from rising too high after eating. The fiber in oranges can grab cancer-causing chemicals and keep them away from cells of the colon, providing yet another line of protection from colon cancer. And the fiber in oranges may be helpful for reducing the uncomfortable constipation or diarrhea in those suffering from irritable bowel syndrome.
In addition to oranges' phytonutrients, vitamin C, and fiber, they are a good source of folate, vitamin A (in the form of carotenoids), vitamin B1, potassium, copper, pantothenic acid, and calcium.
An orange a day may help keep ulcers away, according to a study published in the Journal of the American College of Nutrition. In this study, researchers evaluated data from over 6,000 adults enrolled in the Third National Health and Nutrition Examination Survey. Study participants with the highest blood levels of vitamin C had a 25% lower incidence of infection with Helicobacter pylori (H. pylori), the bacterium responsible for causing peptic ulcers and in turn, an increased risk for stomach cancer. Researchers are uncertain whether H. pylori lowers blood levels of vitamin C or if high blood levels of vitamin C help protect against infection—either way, eating an orange or drinking a glass of orange juice each day may help prevent gastric ulcers. Lead researcher in this study, Dr. Joel A. Simon at the San Francisco VA Medical Center, urges people who have tested positive for H. pylori to increase their consumption of vitamin C-rich foods since this may help them combat H. pylori infection.
New research published in the American Journal of Clinical Nutrition adds to the evidence that enjoying a daily glass of freshly squeezed orange juice can significantly lower your risk of developing rheumatoid arthritis.
Data collected by the European Prospective Investigation of Cancer Incidence (EPIC)-Norfolk study, a population-based, prospective study of over 25,000 subjects, showed that study participants with the highest daily intake of the carotenoids, zeaxanthin and beta-cryptoxanthin, had a much lower risk of developing rheumatoid arthritis compared to individuals consuming the least of these beneficial phytonutrients. Those whose intake of zeaxanthin was highest were 52% less likely to develop rheumatoid arthritis, while those with the highest intake of cryptoxanthin had a 49% reduction in risk. Pretty dramatic benefits for doing something as simple as enjoying a glass of freshly squeezed orange juice each day!
Oranges are one of the most popular fruits around the world. While they are delightful as a snack or as a recipe ingredient, for many Americans, it is their juice that is most associated with good health, having a reputation for being an integral part of a healthy breakfast.
Oranges are round citrus fruits with finely-textured skins that are, of course, orange in color just like their pulpy flesh. They usually range from about two to three inches in diameter.
Oranges are classified into two general categories—sweet and bitter—with the former being the type most commonly consumed. Popular varieties of the sweet orange (Citrus sinensis) include Valencia, Navel and Jaffa oranges, as well as the blood orange, a hybrid species that is smaller in size, more aromatic in flavor and has red hues running throughout its flesh. Bitter oranges (Citrus aurantium) are oftentimes used to make jam or marmalade, and their zest serves as the flavoring for liqueurs such as Grand Marnier and Cointreau.
Oranges originated thousands of years ago in Asia, in the region from southern China to Indonesia from which they spread to India. Although Renaissance paintings display oranges on the table in paintings of The Last Supper, the assumption that they were grown in this region at this time seems to be erroneous since oranges were not cultivated in the Middle East until sometime around the 9th century. Sweet oranges were introduced into Europe around the 15th century by various groups including the Moors, and the Portuguese as well as the Italian traders and explorers who found them on their voyages to Asia and the Middle East.
Orange trees began to be grown in the Caribbean Islands in the late 15th century after Christopher Columbus brought the seeds there on his second voyage to the New World. Spanish explorers are responsible for bringing oranges to Florida in the 16th century, while Spanish missionaries brought them to California in the 18th century, beginning the cultivation of this citrus fruit in the two states widely known for their oranges.
Before the 20th century, oranges were very expensive and therefore they were not regularly consumed, but rather eaten on special holidays such as Christmas. After more efficient means of transportation were developed, and food processors invented methods for utilizing orange by-products such as citric acid and bioflavonoids, the price of oranges dropped, and they could be consumed on a wide scale, as they are today. Currently, the countries that are some of the largest commercial producers of oranges include the United States, Brazil, Mexico, Spain, China and Israel.
Oranges do not necessarily have to have a bright orange color to be good. In fact, the uniform color of non-organic oranges may be due to injection of Citrus Red Number 2 (an artificial dye) into their skins at the level of 2 parts per million. Whether organic or not, oranges that are partially green or have brown russetting may be just as ripe and tasty as those that are solid orange in color. Avoid those that have soft spots or traces of mold. And, because oranges are among the top 20 foods in which pesticide residues are most frequently found, buy organic oranges whenever possible.
Choose oranges that have smoothly textured skin and are firm and heavy for their size. These will have a higher juice content than those that are either spongy or lighter in weight. In general, oranges that are smaller will be juicier than those that are larger in size, as will those that feature thinner skins.
At WHFoods, we encourage the purchase of certified organically grown foods, and oranges are no exception. Repeated research studies on organic foods as a group show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchased of certified organic foods, including oranges. In many cases, you may be able to find a local organic grower who sells oranges but has not applied for formal organic certification either through the U.S. Department of Agriculture (USDA) or through a state agency. (Examples of states offering state-certified organic foods include California, New York, Oregon, Vermont, and Washington.) However, if you are shopping in a large supermarket, your most reliable source of organically grown oranges is very likely to be oranges that display the USDA organic logo.
Oranges can either be stored at room temperature or in the refrigerator, depending upon your preference. They will generally last the same amount of time, two weeks with either method, and will retain nearly the same level of their vitamin content. The best way to store oranges is loose rather than wrapped in a plastic bag since if exposed to moisture, they can easily develop mold.
Orange juice and zest can also be stored for later use. Place freshly squeezed orange juice in ice cube trays until frozen, and then store them in plastic bags in the freezer. Dried orange zest should be stored in a cool, dry place in an airtight glass container.
For some of our favorite recipes, click Recipes.
If you'd like even more recipes and ways to prepare oranges the Nutrient-Rich Way, you may want to explore The World's Healthiest Foods book.
|vitamin C||69.69 mg||93||27.2||excellent|
|fiber||3.14 g||13||3.7||very good|
|vitamin B1||0.11 mg||9||2.7||good|
|pantothenic acid||0.33 mg||7||1.9||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%